The present disclosure relates to breathable film covers for window structures. More particularly, the disclosure relates to breathable multilayer film covers that reflect light or absorb ultraviolet rays.
In designing buildings, natural light is a consideration for architects, builders and owners. Allowing natural light into buildings is an attractive construction option. But the sunlight causes heat, increasing energy consumption and cooling costs. Rather than sacrificing the beauty of natural light for energy savings, window film covers can be applied to existing or new windows for energy savings and other benefits.
Film covers for window structures have been used to filter ultraviolet (UV) rays and/or reflect light from a window pane. Solar control films limit incoming light and UV rays and reduce glare. Polymeric films, such as polyester, polyethylene and polypropylene, have been used. Solar control films can reduce energy costs, lower energy consumption, minimize glare, minimize fabric fading, and reduce eye strain. Many window films perform these functions only for glass windows.
Window panels, plates and panes can be made out of materials other than glass, such as plastic materials including polycarbonate, polyacrylate, and polymethyl methacrylate (PMMA). Such plastic materials are strong, light-weight, shatter-proof and clear, and they may be used for window structures such as skylights, verandas, sunrooms and the like.
Certain problems may develop when metalized polymeric films are attached to polycarbonate, polyacrylate and PMMA plates. Bubbles, craters or tunneling may appear when certain metalized films are applied to plastic plates. Plastic plates, such as polycarbonate and polyacrylate plates, contain moisture that may create defects at the interface of the adhesive/film and the plate when the plate has moisture escape. Defects may appear in a polymeric film that is impervious to moisture.
U.S. Pat. No. 6,270,887 discloses a breathable film that allows moisture to escape to minimize objectionable bubbles, craters and tunnels at the interface between the film and the plastic plate. That patent discloses a metalized polymeric film that is breathable and capable of adhering to polycarbonate and polyacrylate plates without developing bubbles, craters or tunnels as a result of moisture escaping from the plastic plate material.
U.S. Pat. No. 6,270,887 discloses a metalized plasticized polyvinyl chloride (PVC) film, wherein the plasticized PVC film has a metallization coating. An adhesive including a UV absorber forms a layer on the metallization coating. An anti-scratch/anti-static coating is provided on the other surface of the PVC film that does not include the metallization coating. The plasticized PVC film with the metallization coating is permeable to water and allows moisture to escape from the plastic window structures. The film also can act as a light shield or as a UV filter.